- Day Three
acus01 kwns 012001
Storm Prediction Center ac 011959
Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
0259 PM CDT Wednesday Jul 01 2015
Valid 012000z - 021200z
..there is a slight risk of severe thunderstorms from parts of eastern Kansas and MO
to eastern Tennessee and northern al/GA...
..there is a marginal risk of severe thunderstorms over portions of the
northern/Central Plains to the southern Appalachians and southeast
..there is a marginal risk of severe thunderstorms over the northeast US...
..There is a marginal risk of severe thunderstorms over parts of Arizona...
Clusters of severe thunderstorms are possible today over parts of
Missouri...possibly into neighboring eastern Kansas...offering
potential for large hail...damaging gusts and a couple tornadoes.
Damaging gusts and isolated hail also are hazards from severe storms
moving from middle Tennessee and northern Alabama into the southern
Appalachians region. Isolated severe storms are possible over parts
of New York and New England...as well as the northern and central
Great Plains and Arizona.
Forecast remains on track for this region.
..TN to northern Georgia...
Given ongoing convective trends across middle and eastern Tennessee into
northern Alabama and a moderately unstable environment farther downstream
into northern Georgia...the slight risk and severe wind probability have
been expanded southeastward to include much of the rest of northern Georgia. 12z
4 km NAM agrees with this scenario for a potential severe weather
threat to move a little farther to the southeast to include the
Atlanta metropolitan area...with storms then weakening this evening as the
boundary layer stabilizes.
..northern High Plains...
Current rap-based objective analysis suggests a corridor of MLCAPE
500-1000 j/kg extended from north-central into eastern Montana through
western/southern South Dakota. Models continue to suggest the risk for severe storms
should be marginal as a compact shortwave trough moves southeastward from
Canada across this region.
..central New York...
Given convective trends...a small portion of central New York has been
removed from a marginal severe risk.
Previous discussion... /issued 1119 am CDT Wednesday Jul 01 2015/
..TN valley into al/GA...
A remnant mesoscale convective system from overnight convection is tracking southeastward
across parts of western KY/TN. The air mass downstream of the mesoscale convective system
is very moist and should become moderately unstable this afternoon
with MLCAPE values of around 1500 j/kg. Thunderstorms are likely to
re-intensify along the leading edge of the mesoscale convective system...posing a threat of
locally damaging winds as they track across Tennessee into parts of al/GA.
Despite the widespread convection that affected this area last
night...rapid heating is occurring over parts of MO into eastern Kansas.
A shortwave trough evident over eastern Nebraska will track
southeastward and likely aid in convective development by middle/late
afternoon over this region. Low level and deep layer shear will
strengthen through the day...with supercell storm structures likely.
Hail and damaging winds are the main threats...but considerable
veering of low level winds and effects of remnant outflow boundary
may result in isolated tornadoes over western MO/eastern Kansas. Storms
are expected to congeal into another mesoscale convective system during the
evening...tracking into Arkansas.
..Mt into Nebraska...
Various 12z model solutions show isolated convective cells and
clusters along a corridor from northeast Montana into eastern Nebraska this
evening. Due to uncertainties of areal coverage will maintain only
marginal risk at this time...but portions of this area could be upgraded
to slight risk later today.
The current forecast appears on track with only slight adjustment.
Scattered thunderstorms are expected to develop this afternoon over
New York beneath a cool upper trough...spreading eastward into much of New
England by evening. The stronger cells could have gusty winds and
some hail. Present indications are that the severe threat will
Widespread thunderstorms last night have tended to stabilize the
region somewhat. However...isolated strong to severe storms will be
possible once again this afternoon and evening as activity forms
over the higher terrain of eastern Arizona and propagates westward.
Favorable effective shear profiles suggest some risk of rotating
storms over north central Arizona...where marginal hail probabilities
have been added.
acus11 kwns 012221
sels mesoscale discussion
Storm Prediction Center mesoscale discussion 012220
Mesoscale discussion 1272
National Weather Service Storm Prediction Center Norman OK
0520 PM CDT Wednesday Jul 01 2015
Areas affected...portions of far northestern MS...nrn/cntrl Alabama...nrn/cntrl
Georgia...southeastern Tennessee...western NC...and far western SC
Concerning...Severe Thunderstorm Watch 382...
Valid 012220z - 012315z
The severe weather threat for Severe Thunderstorm Watch 382
Summary...while an isolated strong/gusty wind threat continues in
and near ww 382...the increasingly marginal severe risk will
preclude the need for an additional watch...and ww 382 will be
allowed to expire at 23z.
Discussion...thunderstorms which moved southeastward across Tennessee and northern Alabama/Georgia
earlier this afternoon have become increasingly displaced from
stronger middle-level flow to their northwest. Recent radar imagery shows
several ongoing clusters of strong convection extending along an
instability gradient/differential heating boundary from northestern MS to
central al/GA. While MLCAPE of 1500-2000 j/kg estimated by rap
mesoanalysis along and S of this boundary should allow these storms
to continue for the next several hours as they move east-southeastward with
time...limited effective bulk shear owing to weaker middle-level winds
with southward extent should keep storms from organizing on any more than
a brief and isolated basis...with occasional strong/gusty winds the
main threat. Therefore...ww 382 will be allowed to expire on
schedule at 23z...and no additional watch appears necessary at this
..please see www.Spc.NOAA.Gov for graphic product...
Latitude...Lon 33608731 34248855 34508829 34098671 34108611 34378530
35078481 35728396 35518321 34778293 32888378 32788460